For a greater range of motion and comfort while practicing yoga, many women -- and some men -- choose to wear pants or tights that sit very close to the skin. Avoid showing your panty line during downward facing dog by choosing a pair of underwear that also conforms to your body.
Wear No-Show Underwear
Many lingerie brands carry a seamless or "no show" line of underwear. These may come in a variety of styles, including boy short, bikini, brief, thong and hip hugger. The commonality they all share is the material with which they are made -- typically nylon or spandex. As with any underwear worn during exercise, it's important to make sure that the pair you purchase has a crotch made of a more breathable material, such as cotton. This allows air to flow and prohibits the growth of bacteria when you sweat.
Wear a Thong
There is currently some debate on the subject of wearing a thong to exercise. Some health experts claim that the thong can move fecal matter from the anus to the vagina during intense physical activity. This can cause urinary tract infections and bacterial vaginosis. However, many women, including writer Ami Angelowicz of The Frisky, feel more comfortable practicing yoga in a thong and say that women who are uncomfortable are merely wearing the wrong size. Wearing a thong with yoga pants would eliminate panty lines, but it may be wise to consider wearing one to a lower impact class and not to an intense hot yoga session.
Another hotly debated method of reducing underwear lines in yoga pants is to just not wear any. Some women may feel uncomfortable with this technique, but underwear truly isn't necessary. As long as the fabric of your pants will wick away moisture and allow air to flow around your vagina, you greatly decrease your risk for infection and discomfort. Look for pants with a "gusseted" crotch.
Underwear for Men
Because most men practice in looser pants, the problem of visible underwear lines is not as common. Those who prefer to work out in tights can choose to wear gym shorts over the top or form-fitting briefs or boxer briefs underneath. Many exercise shorts designed for men -- such as those used for biking or jogging -- have built-in underwear. Men will be more comfortable in yoga's more difficult positions with the support provided by underwear, so going without is not usually a good option.